<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .box>div{
            width: 200px;
            height: 200px;
        }
        .box>div:nth-child(1){
            background-color: red;
        }
        .box>div:nth-child(2){
            background-color: yellowgreen;
        }
        .box>div:nth-child(3){
            background-color: gray;
        }
        /* div{
           background-color: #ccc; 
        } */
    </style>
</head>
<body>
    <div class="box">
        <div>1</div>
        <div>2</div>
        <div>3</div>
        <p>4</p>
    </div>
</body>
</html>